It is well known, that the mechanism of natural plant protection against any stress has chemical basis (Zaitlin and Palukaitis, 2000). Plants have a non-specific defense system, which is realized by synthesizing non-specific stress-ferments and a gene-controlled defense system, which is realized by synthesizing the specific and non-specific stress-proteins controlled by genetic information (Tarchevsky, 2001). The system of plant protection mechanisms is initiated through the following process. Stress effects plant cells either physically or chemically. This effect activates the signal system (formation of the special signal molecules) of the cell, which transforms the information about stress to plant nucleolus and other plant organelles, which control plant metabolism. After receiving the information of incoming stress, processes for synthesizing non-specific stress ferments begin. If the nucleolus of the plant can recognize the type of stress, using the specific signal system, than the nucleolus will find the information in the DNA about the specific stress protein synthesis that is necessary. The information RNA transforms this information sending new orders to organelles, which start to synthesize the right stress proteins. The newly synthesized specific and non-specific stress-proteins than move to the stress location and reduce the negative influence of the stress or of the attacks of the stress factor (Tarchevsky, 2001).
The key factor for successfully protecting plants against stress is to provide the right and timely information about stress, which is generated by a chemically based system. Specific or nonspecific signal molecules transport the information between stress locale and area of non-specific stress ferments synthesis, between stress locale and gene-apparatus and between gene-apparatus and area of specific stress ferments synthesis (Tarchevsky, 2001). Scientific research has demonstrated that when plants are treated by substances or by physical effects, which initiated or simulated stress or by substances which informed organisms about stress, this results in the formation of specific and non-specific stress-proteins and other stress-protecting substances without the real stress (Tarchevsky, 2001; Montesinos et al., 2002; Struszczyk et al., 2005). The effect of plant “hardening” resulting from the treatment of plants with low levels of stress is a well known mechanism. As a result the plant immune system is ready for the stress and the plant can thus protect itself much more efficiently against damage from the incoming real stress. This means that it is possible to initiate (trigger) the plant defense mechanism (before the actual attacks by dangerous stress), by using low levels of stress simulations which prepare and ready the organisms to increase the plant's resistance against the anticipated incoming real and dangerous stress. The substances that can do this, will be called activators.
The second component of the background of the invention is: biogeochemically active Si. There is much available data, which show that the application of Si fertilizers or Si soil amendments increases plant resistance against stresses (Snyder et al., 2006). There are also many explanations that are available regarding the actual mechanism of Si effect on plant's increased resistance against stresses. This increased resistance is either due to the accumulation of absorbed Si in the epidermal tissue, or the expression of pathogenesis-induced host defense responses (Snyder et al., 2006). Accumulated monosilicic acid polymerizes into polysilicic acid and then transforms to amorphous silica, which forms a thickened Si-cellulose like membrane which can be associated with pectin and calcium ions (Hudson, Sangster, 1988). This means, that a double cuticular layer protects and mechanically strengthens the plants (Ma, Takahashi, 2002). Silicon may also form complexes with organic compounds in the cell walls of epidermal cells, thus increasing their resistance to degradation by enzymes released under stresses. However, the investigation has shown that the reinforcement of the mechanical plant protection can provide only a portion of the plant defense, initiated by Si fertilizers (Belanger, 2005). Our research and research conducted by other scientists have demonstrated that a biochemical mechanism exists for plant protection, which is triggered when soluble Si compounds are applied to the plant (Matichenkov, Bocharnikova 2004). Considering that the application of Si fertilizers increases the content of antioxidants in plants (Belanger, 2005; Snyder et al., 2006) and polysilicic acid can be used for the protection of plants against low temperatures via synthesis of the organic molecules (Banerjee, 2001) the following hypothesis can be formulated: Si can control the synthesis of stress-proteins and other substances for plant protection against stresses. (Matichenkov, Biel, 2006).
The integration of two constituents is the base of the subject hypothesis and invention: (a) starting with special substances' synthesis (enzymes of antioxidant defense, stress proteins, etc.) as the answer of the genetic apparatus in living systems (any plants) to stresses, and (b) additional non enzyme synthesis of the same substances on the polysilicic acid matrix. In this case, a silicic matrix structure is specified by proteins, which were primary synthesized by the genetic apparatus. The function of the Si-matrix, in the defense system, is making additional synthesis of stress proteins without the direct participation of the genetic apparatus and this can explain the known phenomenon of why Si is a protection agent. This means that Si-base synthesis saves living organisms (plants) a lot of energy, thus providing more resistance to stresses.
The hypothesis formulated here together with basic information about the function of the natural plant defense system, which was described above, open the way for new products for increasing natural plant defenses, against any stress, according to the present invention.